Aetna Inc. 's Aetna U.S. Healthcare unit is revamping its contracts with about 300,000 doctors in the face of criticism over so-called gag clauses, patient privacy and other issues that have made the big insurer a target of the American Medical Association.

The new contracts contain language explicitly encouraging doctors to discuss with patients all information pertinent to their care as well as how the doctors are paid by Aetna U.S....